**4.2** *Vitis davidii* **(spine grape)**

*Vitis davidii* var. Forex belongs to the East Asian Vitis spp. and is one of the main wild grape species growing in the East Asian region. It is also known as Spine grape, because its shoots, petioles, and veins are densely covered by spines at 1–2 mm long [18]. The spine grape is mainly distributed in the mountains covered by the subtropical rainforest to the south of the Yangtze River. Huaihua county in Hunan province and Chongyi county in Jiangxi province are the most representative regions for spine grapes because of their wide distribution in those areas [19]. As spine grapes originated from the subtropical humid areas of southern China, this variety showed strong tolerances to high temperatures, high humidity, and resistance to diseases, such as spot anthracnose, white rot disease, and anthracnose [19].

Spine grape was used as table grape years ago, because of its larger berry size compared to other wild species, with an average fruit weight between 3.0–4.5 grams, and a total soluble solid range of 14.5%–16.0% [20]. Recently, with the rapid increase of cultivated area, only a small quantity of spine grapes was made available as fresh edible fruit and a major portion tend to be abandoned each year. Researchers have found that the intense process of converting the Spine grape to wine not only prevents the wastage of grape fruits but also brings high economic benefits to local growers [21]. More so, the development of new cultivars also promotes Spine wine production.

Meng analyzed the physicochemical parameters and aromatic components of nine clones of spine grape from Zhongfang County (Hunan Province, China) [22]. The berry weight, total soluble solids, titratable acids (expressed as equivalent of tartaric acid), and pH were found to be in the ranges of 2.08–3.88 g, 9.5–15.4 Brix, 1.99–3.93 g/L, and 3.16–3.77, respectively, indicating that the clones are more suitable for winemaking compared to the wild spine grape.

Flavor compounds are important quality indexes for wine production, which are mainly derived from grape berries, and can be affected by soil, altitude, slope, and cultivation management among others. In two different studies, Meng [22] and Zhao [18] respectively evaluated the free aromatic components and the influence of different altitudes on flavor compounds of Spine grape clones, 'Ziqiu', 'Seputao',' Miputao',' Xiangzhenzhu', 'Tianputao', and' Baiputao'. According to the findings, C6 compounds were the most abundant aromatic components in various spine grape clones, accounting for 71–94% of the total aromatic compounds identified. The most predominant compounds were (E,E)-2,4-hexadienal and (E)-2-hexenal [22]. At the height of 700 meters above sea level, the contents of anthocyanins, non-anthocyanin phenolic compounds, and aroma compounds in 'Seputao' were significantly higher than those at 240 meters and 600 meters altitudes. However, at the altitude of 240 meters, the contents of reducing sugars, anthocyanins, nonanthocyanin phenolic compounds, and aroma compounds in'Ziqiu'were the highest among three altitudes 240, 600, and 700 meters [18].

Meng [19] also investigated the phenolic profiles and antioxidant activity of four spine grapes cultivars (Junzi #1, Junzi #2, Liantang, and Baiyu) from Chongyi County, Jiangxi Province, China. It was revealed that Junzi #1 had the highest phenolic content and the strongest antioxidant capacity, HPLC analysis also showed that the (+)-catechin was the most abundant phenolics while hydroxycinnamic acids were the major phenolic acids [19]. Regarding some individual phenolic compounds, JZ-1 contained the highest p-coumaric acid, coumarin, transresveratrol, and (+)-catechin contents, while BY had the highest rutin and quercetin contents.

The same researcher also characterized the phenolic profile of young wines made from spine grape. Like most vinifera wines, flavan-3-ols were the major class of phenolic compounds present in spine grape wines while quercetin-3-rhamnoside was the main singular flavonol [21]. In addition, syringetin-3-glucoside and dihydroquercetin-3-hexoside were the characteristic flavonols of red and white spine grape wines, respectively, while coutaric acid and fertaric acid were the dominant phenolic acids [21].

Organic acids play a key role in grape and wine quality. The acid component of grape berries mainly consists of tartaric acid, malic acid, lactic acid, acetic acid, citric acid, and oxalic acid. The total acidity in *Vitis davidii* Foex fruits is typically higher than in *Vitis Vinifera* varieties, resulting in high acidity in the fermented wine [23] (around 8 grams of tartaric acid per liter of wine after malolactic fermentation), which has been a major constraint on the Spine wine industry.

The effect of deacidification reagents (KHCO3 and CaCO3) on the aroma compounds of spine wine was studied by Li [23]. The results showed that the OAVs of compounds with flavors of fruit, cheese, caramel, and chemical were reduced. However, sensory evaluation revealed that the mouthfeel and aroma characteristics of spine wine were improved after deacidification.

Due to the relatively low sugar content in Spine grapes, ranging from 12.3 to 15.9°Brix, an early winemaking study showed that sugar addition was required for red Spine wine production to improve wine quality [24]. Conversely, this neutral grape characterized by low sugar levels and high acidity is suitable for making distilled spirit-based beverages [25].

Currently, high quality Spine grape spirits are produced by several local wineries and are welcomed by local consumers. Xiang [26] identified the key odor-active volatile compounds in the head, heart, and tail fractions of freshly distilled spirits from Spine grape (*Vitis davidii* Foex) wine. The volatile compounds had considerably varying amounts in the head, heart, and tail fractions due to differences in boiling point and solubility, which resulted in various evolution patterns during distillation. The head fraction was characterized by fruity, fusel/solvent notes owing to higher concentrations of higher alcohols and esters, while the tail fraction had more intense smoky/animal, and sweaty/fatty attributes due to higher concentrations of volatile phenols and fatty acids [26].

#### **4.3** *Vitis quinquangularis* **Rehd**

*Vitis quinquangularis*, known locally as the pentagon-leafed grape, is distributed south of the Yellow River in regions that have sufficient sunshine and are at an altitude of <1500 m.

*Vitis quinquangularis* is an important research grape with high resistance to powdery mildew due to its high resveratrol content [27].

Selection studies have also been conducted on *V. quinquangularis* in the central part of China. Liang [28] revealed that this cultivar contained different anthocyanins compared to *Vitis davidii*. For example the 'Xiangshan No. 4' (*V. quinquangularis*) contains high levels of 3<sup>0</sup> ,4<sup>0</sup> -substituted anthocyanins, low levels of flavonols, and low 3<sup>0</sup> ,4<sup>0</sup> -substituted flavan-3-ols, indicating that the F3<sup>0</sup> H branch pathway is the principal carbon pathway synthesizing mainly 3<sup>0</sup> ,4<sup>0</sup> -substituted anthocyanins [28].

*Winemaking in Cold Regions with Buried Viticulture in China DOI: http://dx.doi.org/10.5772/intechopen.99614*

Also, the grape berries of *Vitis quinquangularis* ripen with low sugar content and high acidity, but with dark-colored skin. Their wines have a characteristic varietal aroma and a pronounced acid and tannic sensation [28, 29].

Fang examined the effects of different processes on the flavor components of wild *V. quinquangularis* wine produced in the Qinba mountain region [30]. The findings demonstrated that alcohol was the most important aroma compound in *V. quinquangularis* wine, with the highest relative contents of benzene ethanol and pentanol. After six months of aging, the aroma quality of carbonic macerated wine was better than that of the traditional process [30].

Liu also proved that carbonic maceration increased the contents of esters, acids, and phenols as well as the species and contents of volatile compounds in wines [31]. The combination of carbonic maceration and malolactic fermentation could result in more volatile compounds in wines, giving such wines a unique taste distinct from traditional wines [31]. Similar results were reported in *V. amurensis* wines, with Pei revealing that carbonic maceration decreased the fruit aroma while increasing the flower aroma and overall aroma quality of *V. amurensis* wine [17].
